Add support for a real 10-bit dac

git-svn-id: https://bucket.mit.edu/svn/nilm/zoom@8673 ddd99763-3ecb-0310-9145-efcb8ce7c51f

firmware/dac.h

@@ -3,16 +3,22 @@
 
 #include "config.h"
 
-#define FAKE_BITS
+#define DAC_TYPE 2
 
-#ifdef FAKE_BITS
-  /* fake compressed range with random lookup bits */
+#if DAC_TYPE == 0
+  /* AD5542, normal 16-bit range */
+  #define DAC_BITS 16
+  #define __dac_actual(x) (x)
+#elif DAC_TYPE == 1
+  /* AD5542, fake 10-bit range using random lower bits */
   #define DAC_BITS 10
   #define __dac_actual(x) (dac_lookup[(x)&1023])
+#elif DAC_TYPE == 2
+  /* MAX504, true 10-bit DAC */
+  #define DAC_BITS 10
+  #define __dac_actual(x) ((x) << 2)
 #else
-  /* normal range */
-  #define DAC_BITS 16
-  #define __dac_actual(x) (x)
+  #error Unknown DAC type
 #endif
 
 #define DAC_LOW 0